Prevention of diffusion of sensitizing dyes



April 29,1941. Y B. H. CARROLL 2,239,699

PREVENTION 0F DIFFUSION OF SENSITIZING DYES' Filed Feb. 20, 19.40

.5u/apart.

' BMW/v -CARRULL INVENTOR 2. /4 Wm BYgafMl/C/ ATT NEYS silvery. halide emillsior Patented Apr. 29, 1941 l 2,239,699

Whepevergtwo, 91 m0 layers;of;.difierei111;alle"` superpose@ ,en on'slde' ifa-.support .(Whth f me; layers; aresenaratd-;hyf er1-'meri 001,101@ (i ft ,i layer or not), as in monopack color processes, J gram-mole of"`silver halidds overco rie iodide one vof,gtheffprrinipalfgdiglculties encountered is .an.... ordinary .pine-sensitive@.,gelatino-silyer-'" the diffusion of sensitizing dyes from one layer w' bromlodideniiiliohtluppercoat show to another. Diusion becomes very noticeable appreciable green sensitivity owing to diffusion when an ordinary vblue-sensitive silver halide of the'cyaninev iodide from the vgreen-sensitive emulsion layer is superposed on a silver halide layer to the blue-sensitive layer. If, however, emulsion layer which is sensitized to green light sodium perchlorate or sodium periodate is added by means of sensitizing dyes, the sensitizing to either the green-sensitive or the blue-sensidyes `in the green sensitive layer diffusing into tive emulsion layers, preferably the latter, in a the blue-sensitive layer. concentration of 10 grams per gram-mole of I have now found that diiusion of quaternary silver halide, prior to coating, the diffusion of ammonium salt type sensitizers (e. g. cyanine the sensitizing dyes is reduced to a negligible` salts, hemicyanine salts and styryl salts) from value. The sodium perchlorate (or periodate)v emulsion layers can be prevented by incorpois advantageously incorporated in the emulsion rating in the emulsion layer containing the senin the form of a concentrated aqueous solution. sitizer or in an emulsion layer superposed there- My invention is, of course, directed primarily on, a perhalogenate salt other than a quaternary f to photographic elements made `up employing ammonium perhalogenate. 25 the customary gelatine-silver-halide developing- It is, accordingly, an object of my invention out emulsions. However, silver bromide emulto provide a method for preventing diffusion of sions where the carrier is asubstance other than sensitizing dyes in photographic emulsions. A gelatin, e. g. a. cellulose derivative or resinous further object is vto provide new prim-,ograpliicAv material can also be employed. elements. Other objects will appear hereinaf- The accompanying drawing shows, diagramter, matically, a photographic element, prepared in As'perhalogenate salts, I have found that the accordance with` one embodiment of my invenalkali metal perhalogenates are inert'toward the tion, comprising a support coated with a greenemulsion and are advantageously employed. The sensitive gelatina-silver-bromiodide emulsion perhalogenate salt is advantageously incorpolayer sensitized with 2,1'diethyl3,4benzothia rated in the emulsion after the sensitizing dyes, 2*-cyanine iodide, the green-sensitive emulsion inasmuch as the sensitizing dyes are likely to be layer being coated with a blue-sensitive gelatlcoagulated (and therefore to sensitize unsatisino-silver-bromlodide emulsion layer containfactorily), if the perhalogenate salt is added to mg sodium perchlorate, the emulsion before the sensitizing' dyes. The 4.0` what I claimag m inv n o f perhalogenate salt is advantageously empIOyed be rsecured by Letterys Paeit nognghget in i; 1concentrati'orr;1 several times tllilat oi' thiszn- States is: l y sit ng dyes. us, whereas t e sensi nel/- dyes are employed in concentrations of 10 to 20 site gtilor'lrslgg 1:1153 12115211? senmg. per liter of emulsion containing 0.25 gram- Snizer and' containing a perhaiogensate seul; mole of silver halide, the perhalogenate salts are other th sa' advantageously employed in concentrations very' te M ,a Quaternary ammonium 'perhalo' considerably larger than these values, viz. 0.5 to gena L 2. A photographic gelatino-silver-halide emul- 5 grams per liter of emulsion containing 0.25 i gram-mole of silver halide, i. e. 2 to 20 grams 50 sion sensitized with a' Quaternary mmOnillm r gram-mole of silver halide. l salt sensitizer and Containing a Perhalogenatc My invention is particularly useful for pre- S8117 Other than Quaternary ammonium perventing diffusion of sensitizing dyes from a halogenate.

green-sensitive emulsion layer to an ordinary 3- APhOtOSraphic gelatino-silver-halide emulbme sensmve emulsion layer Superposed theresion sensitized with a Quaternary ammoniumV 4. A photographic gelatino-silver-halide emulv sion sensitized with a quaternary ammonium salt sensitizer and containing an alkali metal perchlorate.

5. A photographic gelatine-silver-halide sensitized with a cyanine salt sensitizer and containing an alkali metal perchlorate.

6. A photographic element comprising two gelatino-silver-halide emulsion layers superposed on one side of a support, the one layer being sensitized to green light with a sensitizing dye of the Quaternary ammonium salt type, and the other layer containing a perhalogenate salt other than a quaternary ammonium perhalogenate. 7. A photographicl element comprising two gelatina-silver-halide emulsion layers superposed on one side of a support, the one layer being sensitized to green light with a sensitizing dye of the quaternaryammonium salt type, and

the other layer containing an alkali metal `perhalogenate.

8. A 'photographic element comprising two the other layer containingan alkali metal perchlorate.

l0. A photographic element comprising two gelatino-silver-halide emulsion layers superposed on o ne side of a support, the one layer being sensitized to green light with a sensitizinz dye of the Quaternary ammonium salt type, and the other layer containing an alkali metal Derchlorate in a concentration of from about 2 to about 20 grams per gram-mole of silver halide in the layer.

. BURT H. CARROLL. 

